The three final episodes of Kuma Miko. Those who have watched the show should know why this is a show perfect for this thread, if not...well. Let's just say it goes from mildly cruel (but kinda funny) humor, to straight out brain washing and traumatic experiences for the main character, and the anime staff presenting it all as some kind of happy ending, though it should be pretty clear to anyone watching that things as they are in the ending just looks and sounds...wrong.

The final episode of Magical Warfare, and as far as stuff I have recently seen, nothing even comes close. When the episode begins by skipping a lot of stuff when it was uncalled for from the previous episode, you know that you are in for one helluvan awful experience. Add on top of that characters making fools of themselves for all the wrong reasons, a lot of stuff being skipped, and to end the story with stuff far from settled, I think you can figure out the rest.

The last episode of Utawarerumono's anime adaptation was a truly crushing disappointment, but I knew from the moment they veered away from the well-presented fantasy setting and tried to delve into some nonsensical science fiction plot twist crap the ending would be terrible. Every episode after that tore away a little piece of my soul.